Available for Ubuntu:
13.04

Version: 4.0-1~getdeb2~raring

Dolphin is a Gamecube and Wii emulator. Most games run perfectly or with minor bugs. Games are playable at HD quality, up to 1080p. This is a remarkable feature the actual Gamecube and Wii consoles are not capable of. As an open source project everyone can commit improvements. The code is hosted on GitHub. Dolphin is actively developed and almost every day new features are added and bugs fixed as well.

Available for Ubuntu:
12.04, 13.04

Version: 2.16.7-1~getdeb5

Gens/GS is a version of Gens maintained by GerbilSoft. The main goal of Gens/GS is to clean up the source code and combine features from various forks of Gens, as well as improving portability to other platforms.
NOTE: ONLY COMPILED FOR i386!

Version: 2.2.1-1~getdeb1

Pokemon Online is the most popular, accurate, and complete Pokemon battle simulator out there. Available in 11 languages with over 100 themes, it hosts more than a million battles per month. Experience competitive battles across five generations (RBY/Stadium, GSC, RSE, DPPt/HGSS, and Black/White 2) in real time with trainers from around the world!